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Papers by Robert Bereskin

AAPG Bulletin, 1986

Most geologists and engineers are now aware of the large differences in core analysis measurement... more Most geologists and engineers are now aware of the large differences in core analysis measurements performed at bench and overburden conditions. The magnitude of change observed in these measurements is highly variable not only for different rock types, but also for similar lithologies within a single cored interval. Several rock fabric physical properties contribute to the variable stress sensitivity of reservoir rocks; however, the authors believe that the effects of coring, core recovery operations, natural dilation and/or contraction of the rock fabric, and preservation procedures are primarily responsible for increased porosity and permeability at bench conditions. Measurements of pore system parameters in fractured and conventional reservoirs can be achieved using new petrographic methods and special core testing techniques. Fluorescent epoxy impregnations of core samples performed under bench and simulated in-situ conditions of effective stress offer the ability to observe fracture and intergranular porosity at surface and reservoir conditions. Fluorescent microscopy, computer image analysis, and special core permeability testing are combined to document the variation of stress sensitivity within several different reservoir rock types.

AAPG Bulletin, Jun 1, 1991

Since discovery in 1983, the Grant Canyon field has been among the most prolific oil producers (o... more Since discovery in 1983, the Grant Canyon field has been among the most prolific oil producers (on a per-well basis) in the US. Production through June 1990 was 12,935,630 bbl of oil, principally from two wells which in tandem have consistently yielded more than 6,000 bbl of oil per day. The field is hosted by highly porous Devonian dolomite breccia

AAPG Bulletin, Aug 1, 1993

The Madden Deep unit, located in the Wind River basin of central Wyoming, has been a source of na... more The Madden Deep unit, located in the Wind River basin of central Wyoming, has been a source of natural gas production from Upper Cretaceous and Lower Tertiary formations. Drilling in excess of 24,000 ft occurred during the mid-1980s and early 1990s to explore for and develop Paleozoic gas potential. These well bores penetrated the Upper Cretaceous Frontier Formation at depths

Anastamosing, low gradient distributary channels produce ~30 gravity, paraffinic oils from the Mi... more Anastamosing, low gradient distributary channels produce ~30 gravity, paraffinic oils from the Middle Member of the lacustrine Eocene Green River Formation in the south-central portion of the Uinta Basin. This localized depocenter was situated along the fluctuating southern shoreline of Lake Uinta, where complex deposits of marginal-lacustrine to lower delta plain accumulations are especially characteristic.

Anastamosing, low-gradient, distributary channel deposits in the lower and middle members of the ... more Anastamosing, low-gradient, distributary channel deposits in the lower and middle members of the Eocene Green River Formation are the primary oil reservoirs in the south-central portion of the Uinta Basin, Utah. The Eocene depocenter was situated along the fluctuating southern shoreline of Lake Uinta, where complex deposits of the marginal-lacustrine environment were commonly laid down. The Green River Formation contains several fining-upward sequences that can be recognized in outcrop, core, and well logs. Each sequence is about 60 to 120 feet (18-36 m) thick and consists of strata typically 30 to 35 feet (9-11 m) thick that were deposited during multiple lake-level fluctuations. The subaerial to subaqueous channels commonly possess an erosional base and exhibit a fining-upward character. Bedding features commonly range from large-scale trough and planar cross-bedded (or lamination) facies at the base, to a climbing ripple facies near the uppermost bed boundary. The best reservoir quality is typically within the laminated to cross-stratified facies, and the poorest reservoir quality is within the climbing ripple facies which usually possesses more deleterious micas and/or detrital clays. Diagenesis exerts a major control on reservoir quality. Some sandstone beds were cemented early by an iron-poor calcite cement, which was often later leached resulting in good reservoir quality rock with secondary intergranular porosity (up to 20 percent) and permeability (10 to 100 millidarcies [md]). Without early calcite cementation, reservoir quality was often reduced by intense compaction, silicic and ironrich carbonate cements, and authigenic clays.

AAPG Bulletin, 1969

Association Round Table 469 truncatuUnoides, and G. inflata, in ancient Californian sediments sho... more Association Round Table 469 truncatuUnoides, and G. inflata, in ancient Californian sediments should lead to a better understanding of paleobasin oceanography by making it possible to determine sill depths and oxygen minimum distributions. Such studies have obvious applications in the determination of petroleum source rocks, because organic material is preserved in anaerobic conditions but destroyed in aerated sediments.

The mountain Geologist, 2003

Abstract Several oil fields which produce from the lower Green River Formation (Eocene) in the vi... more Abstract Several oil fields which produce from the lower Green River Formation (Eocene) in the vicinity of Pleasant Valley have expanded in recent years into a single large producing area. A 2,000 foot thick interval produces from multiple stratigraphic traps on regional structural dip along the southern margin of the Uinta Basin. One typical reservoir which has been mapped is a channel sand and is part of a fluvial delta system with a southerly source depositing lithic arkoses and feldspathic litharenites. Compaction, alteration, clay precipitation, and carbonate replacement and cementation have resulted in a low porosity and permeability reservoir. Completion procedures can be complicated by migration of fine particles and by acid sensitivity to an abundance of iron rich minerals. Primary production of 60,000 to 100,000 barrels only represents about 5% of the oil in place.

Abstract The upper member of the Guilmette Formation in west-central Utah consists of more than 6... more Abstract The upper member of the Guilmette Formation in west-central Utah consists of more than 600 m of peritidal and subtidal carbonate-platform deposits. Constituent facies range from supratidal dolomitic laminites to subtidal lagoonal stromatoporoidal floatstones, and open marine wackestones. These facies occur in a repetitive series of transgressive-regressive and shallowing upward cycles that persist throughout much of the member and range in thickness from 3 to 44 m, averaging 11 m. The upper member of the Guilmette Formation is divided into four informal units whose lithofacies indicate deepening environments upsection. Unit 1 is dominated by supratidal facies, Unit 2 by intertidal facies, Unit 3 by subtidal, lagoonal facies and Unit 4 by subtidal, open-marine facies. Cycles are present only in the lower three units. Correlation of units, cycles and distinctive beds between measured sections in the study area indicates major differences between the southernmost section and those to the north. The southern section has more regularly spaced cycles, consistently shallower environments and lower sediment accumulation/subsidence rates. These features indicate that the southern section was on the edge of the developing Pilot basin and possibly closer to the paleostrandline. Thick cycles (> 19 m) probably indicate deepening events and may be related to similar events documented elsewhere. Some cycles may have been formed during eustatic sea level rises related to Milankovitch cycles.

AAPG Bulletin, 1994

Eastern Nevada's Grant Canyon and Bacon Flat oil fields show strong evide... more Eastern Nevada's Grant Canyon and Bacon Flat oil fields show strong evidence of formation in a still-active, moderate-temperature geothermal system. Modern manifestations of this system include unusually elevated oil-reservoir temperature at shallow depth, 116-122[degrees]C at 1.1-1.6 km, and dilute Na-HCO[sub 3]Cl thermal waters directly associated with hot oil. Hydrogen and oxygen isotopic compositions indicate that these thermal waters are meteoric

International Journal of Rock Mechanics and Mining Sciences, Apr 1, 1997

Faults, and composite fault and joint networks are common structural and hydrologic elements in r... more Faults, and composite fault and joint networks are common structural and hydrologic elements in reservoirs. The structural and hydrologic architecture of faults is complicated by the formation of striated slip surfaces, cataclasite and gouge, deformation of the adjacent wall rock, and hydrothermal mineralization. A prototype, analytical computer algorithm is presented to model faults as anisotropic fluid conduits, and joints as isotropic conduits. The permeability tensor of the rock mass is determined by the volume averaged contribution of each fault and joint in the population via tensor rotation from the local coordinate system of each fracture to the global, geographic reference frame. Permeability across the fracture walls and the permeability of the rock matrix are also considered in the algorithm. Application to a synthetic network of conjugate fractures illustrates that the anisotropic surface texture of faults is a fundamental feature determining the permeability of the rock mass. Modeling is also conducted to illustrate how changes in the stress tensor affect permeability anisotropy.

AAPG Bulletin, 1993

Fracture production clearly exists in the small oil fields south of Duchesne. Other attempts at e... more Fracture production clearly exists in the small oil fields south of Duchesne. Other attempts at establishing, look-alike production have been mixed due principally to lack of knowledge regarding completion techniques. Horizontal drilling ventures near the zone probably will produce mixed results because of the stratigraphically variable position of the pools themselves. Water zones also have been encountered near the faults,

AAPG Bulletin, 1986

Most geologists and engineers are now aware of the large differences in core analysis measurement... more Most geologists and engineers are now aware of the large differences in core analysis measurements performed at bench and overburden conditions. The magnitude of change observed in these measurements is highly variable not only for different rock types, but also for similar lithologies within a single cored interval. Several rock fabric physical properties contribute to the variable stress sensitivity of reservoir rocks; however, the authors believe that the effects of coring, core recovery operations, natural dilation and/or contraction of the rock fabric, and preservation procedures are primarily responsible for increased porosity and permeability at bench conditions. Measurements of pore system parameters in fractured and conventional reservoirs can be achieved using new petrographic methods and special core testing techniques. Fluorescent epoxy impregnations of core samples performed under bench and simulated in-situ conditions of effective stress offer the ability to observe fracture and intergranular porosity at surface and reservoir conditions. Fluorescent microscopy, computer image analysis, and special core permeability testing are combined to document the variation of stress sensitivity within several different reservoir rock types.

AAPG Bulletin, Jun 1, 1991

Since discovery in 1983, the Grant Canyon field has been among the most prolific oil producers (o... more Since discovery in 1983, the Grant Canyon field has been among the most prolific oil producers (on a per-well basis) in the US. Production through June 1990 was 12,935,630 bbl of oil, principally from two wells which in tandem have consistently yielded more than 6,000 bbl of oil per day. The field is hosted by highly porous Devonian dolomite breccia

AAPG Bulletin, Aug 1, 1993

The Madden Deep unit, located in the Wind River basin of central Wyoming, has been a source of na... more The Madden Deep unit, located in the Wind River basin of central Wyoming, has been a source of natural gas production from Upper Cretaceous and Lower Tertiary formations. Drilling in excess of 24,000 ft occurred during the mid-1980s and early 1990s to explore for and develop Paleozoic gas potential. These well bores penetrated the Upper Cretaceous Frontier Formation at depths

Anastamosing, low gradient distributary channels produce ~30 gravity, paraffinic oils from the Mi... more Anastamosing, low gradient distributary channels produce ~30 gravity, paraffinic oils from the Middle Member of the lacustrine Eocene Green River Formation in the south-central portion of the Uinta Basin. This localized depocenter was situated along the fluctuating southern shoreline of Lake Uinta, where complex deposits of marginal-lacustrine to lower delta plain accumulations are especially characteristic.

Anastamosing, low-gradient, distributary channel deposits in the lower and middle members of the ... more Anastamosing, low-gradient, distributary channel deposits in the lower and middle members of the Eocene Green River Formation are the primary oil reservoirs in the south-central portion of the Uinta Basin, Utah. The Eocene depocenter was situated along the fluctuating southern shoreline of Lake Uinta, where complex deposits of the marginal-lacustrine environment were commonly laid down. The Green River Formation contains several fining-upward sequences that can be recognized in outcrop, core, and well logs. Each sequence is about 60 to 120 feet (18-36 m) thick and consists of strata typically 30 to 35 feet (9-11 m) thick that were deposited during multiple lake-level fluctuations. The subaerial to subaqueous channels commonly possess an erosional base and exhibit a fining-upward character. Bedding features commonly range from large-scale trough and planar cross-bedded (or lamination) facies at the base, to a climbing ripple facies near the uppermost bed boundary. The best reservoir quality is typically within the laminated to cross-stratified facies, and the poorest reservoir quality is within the climbing ripple facies which usually possesses more deleterious micas and/or detrital clays. Diagenesis exerts a major control on reservoir quality. Some sandstone beds were cemented early by an iron-poor calcite cement, which was often later leached resulting in good reservoir quality rock with secondary intergranular porosity (up to 20 percent) and permeability (10 to 100 millidarcies [md]). Without early calcite cementation, reservoir quality was often reduced by intense compaction, silicic and ironrich carbonate cements, and authigenic clays.

AAPG Bulletin, 1969

Association Round Table 469 truncatuUnoides, and G. inflata, in ancient Californian sediments sho... more Association Round Table 469 truncatuUnoides, and G. inflata, in ancient Californian sediments should lead to a better understanding of paleobasin oceanography by making it possible to determine sill depths and oxygen minimum distributions. Such studies have obvious applications in the determination of petroleum source rocks, because organic material is preserved in anaerobic conditions but destroyed in aerated sediments.

The mountain Geologist, 2003

Abstract Several oil fields which produce from the lower Green River Formation (Eocene) in the vi... more Abstract Several oil fields which produce from the lower Green River Formation (Eocene) in the vicinity of Pleasant Valley have expanded in recent years into a single large producing area. A 2,000 foot thick interval produces from multiple stratigraphic traps on regional structural dip along the southern margin of the Uinta Basin. One typical reservoir which has been mapped is a channel sand and is part of a fluvial delta system with a southerly source depositing lithic arkoses and feldspathic litharenites. Compaction, alteration, clay precipitation, and carbonate replacement and cementation have resulted in a low porosity and permeability reservoir. Completion procedures can be complicated by migration of fine particles and by acid sensitivity to an abundance of iron rich minerals. Primary production of 60,000 to 100,000 barrels only represents about 5% of the oil in place.

Abstract The upper member of the Guilmette Formation in west-central Utah consists of more than 6... more Abstract The upper member of the Guilmette Formation in west-central Utah consists of more than 600 m of peritidal and subtidal carbonate-platform deposits. Constituent facies range from supratidal dolomitic laminites to subtidal lagoonal stromatoporoidal floatstones, and open marine wackestones. These facies occur in a repetitive series of transgressive-regressive and shallowing upward cycles that persist throughout much of the member and range in thickness from 3 to 44 m, averaging 11 m. The upper member of the Guilmette Formation is divided into four informal units whose lithofacies indicate deepening environments upsection. Unit 1 is dominated by supratidal facies, Unit 2 by intertidal facies, Unit 3 by subtidal, lagoonal facies and Unit 4 by subtidal, open-marine facies. Cycles are present only in the lower three units. Correlation of units, cycles and distinctive beds between measured sections in the study area indicates major differences between the southernmost section and those to the north. The southern section has more regularly spaced cycles, consistently shallower environments and lower sediment accumulation/subsidence rates. These features indicate that the southern section was on the edge of the developing Pilot basin and possibly closer to the paleostrandline. Thick cycles (> 19 m) probably indicate deepening events and may be related to similar events documented elsewhere. Some cycles may have been formed during eustatic sea level rises related to Milankovitch cycles.

AAPG Bulletin, 1994

Eastern Nevada's Grant Canyon and Bacon Flat oil fields show strong evide... more Eastern Nevada's Grant Canyon and Bacon Flat oil fields show strong evidence of formation in a still-active, moderate-temperature geothermal system. Modern manifestations of this system include unusually elevated oil-reservoir temperature at shallow depth, 116-122[degrees]C at 1.1-1.6 km, and dilute Na-HCO[sub 3]Cl thermal waters directly associated with hot oil. Hydrogen and oxygen isotopic compositions indicate that these thermal waters are meteoric

International Journal of Rock Mechanics and Mining Sciences, Apr 1, 1997

Faults, and composite fault and joint networks are common structural and hydrologic elements in r... more Faults, and composite fault and joint networks are common structural and hydrologic elements in reservoirs. The structural and hydrologic architecture of faults is complicated by the formation of striated slip surfaces, cataclasite and gouge, deformation of the adjacent wall rock, and hydrothermal mineralization. A prototype, analytical computer algorithm is presented to model faults as anisotropic fluid conduits, and joints as isotropic conduits. The permeability tensor of the rock mass is determined by the volume averaged contribution of each fault and joint in the population via tensor rotation from the local coordinate system of each fracture to the global, geographic reference frame. Permeability across the fracture walls and the permeability of the rock matrix are also considered in the algorithm. Application to a synthetic network of conjugate fractures illustrates that the anisotropic surface texture of faults is a fundamental feature determining the permeability of the rock mass. Modeling is also conducted to illustrate how changes in the stress tensor affect permeability anisotropy.

AAPG Bulletin, 1993

Fracture production clearly exists in the small oil fields south of Duchesne. Other attempts at e... more Fracture production clearly exists in the small oil fields south of Duchesne. Other attempts at establishing, look-alike production have been mixed due principally to lack of knowledge regarding completion techniques. Horizontal drilling ventures near the zone probably will produce mixed results because of the stratigraphically variable position of the pools themselves. Water zones also have been encountered near the faults,